Re: [PARAVIRT/x86] BUGFIX: Put a missing paravirt_release_pmd in pgd_dtor

[Jeremy Fitzhardinge <jeremy@goop.org>]

Alok Kataria wrote:
> As it affects only VMI, instead of adding another callback, i have
> hooked on the paravirt_pgd_free call for vmi to release the pgd page.
> Below is the patch. I will run some overnight tests with this patch and
> get back if there are any errors.
>   

I'd forgotten that I'd already added pgd_alloc/pgd_free.  So, yes, just 
use pgd_free.

>> But either way, calling release_pmd here is wrong, since its only meant 
>> to be applied to pmds,
>>     
> Maybe i misunderstand, but that's how it used to work before that
> commit, we had a single call to release_*pd*, no ?
>   

I rearranged things, but I don't remember the details.  I think pd was 
being overloaded for both pgd and pmd, and I split it out so there was a 
specific function for each level.

>>  and it would break the Xen code.
>>     
>
> i see xen doesn't define the alloc_pmd_clone call. 
>   

It defines alloc_pmd, but has no need for alloc_pmd_clone (there's no 
shadow pagetable, so there's nothing to sync).  Zach added specifically 
for vmi's use.

    J